The present invention relates to apparatus for manipulating stacked commodities, particularly paper sheets, and more particularly to improvements in stack transporting apparatus wherein selected stacks of a series or succession of discrete stacks can be removed or diverted from their path for discarding or for transport to one or more processing stations.
It is known to divert selected commodities of a succession of equidistant or randomly spaced commodities by resorting to a so-called diagonal conveyor which is designed to advance selected commodities at a certain angle with reference to the direction of movement of commodities into the range of such diagonal conveyor. The latter can comprise a set of rollers, one or more straight belt conveyors, one or more arcuate belt conveyors, an arcuate switching device or the like. Means is provided to raise the diagonal conveyor into the path of movement of oncoming commodities whereby the diagonal conveyor diverts one or more selected commodities from their original path. The diagonal conveyor is thereupon caused to descend to a level below that of the conveyor or conveyors which define the primary path for the commodities so that the next-following commodities remain undiverted.
A drawback of the above outlined conventional apparatus is that they cannot handle stacks of paper sheets or the like when the stacks must be transported at an elevated speed. Rapid acceleration, deceleration and/or change in the direction of movement of stacks causes them to change their shape so that they cannot be introduced into snugly fitting boxes or other types of receptacles. Moreover, deviation of the shape of transported stacks from their original parallelepiped shape can create problems during other types of further processing, e.g., if the stacks are to be provided with rows of perforations at a predetermined distance from a marginal portion of each sheet in the stack preparatory to insertion of spiral or otherwise configurated binders for conversion of stacks into steno pads, exercise books and analogous stationery products. When the speed of the stacks exceeds a certain limit, the diagonal conveyor is simply incapable of preventing deformation and/or complete collapse of stacks during diversion of stacks from their original path. On the other hand, the trend in paper processing plants is toward a continuously increasing output which renders it necessary to divert selected stacks from their original path as quickly as possible without reducing the speed of the remaining stacks.